How Long Does a Roof Replacement Take?

How Long the Work Takes, and What the National Guides Skip

We get asked this at almost every estimate. The owner wants to know how many days of noise, how long the driveway is blocked, and whether they need to book a hotel. Fair questions.

On our roof replacement page we tell people most homes take two to four working days. Big roofs, steep roofs and tile jobs can take longer, and we put the expected days in the written quote.

The roof maker IKO, in a guide dated May 28, 2025, says a tear off takes about a day on an average size roof and the new roof takes one or two more. That is a fair national number for a simple shingle job. But the guide never mentions a permit or an inspection. It does not talk about heat at all. And it says almost nothing about tile.

Those three things are exactly what stretch a reroof in Ontario. So this page walks through the whole job the way it really runs here, from the day you sign to the day the inspector signs off.

The Whole Job, Start to Finish

Signing the contract. California's sample home improvement contract from the Contractors State License Board has a line for an approximate start date and an approximate completion date. It also has a line that says what counts as substantial start of work. If your contract leaves those blank, ask for them before you sign. The same sample lists a three day right to cancel for most owners, and five days if the owner is over 65.

The permit. A full reroof needs a building permit in Ontario. The city works with an online system called Symbium for detached single family reroof permits, and calls those permits streamlined on its reroof permit page. Your roofer usually pulls it. One more date to know. Per the city's permit FAQ, a permit expires if no work starts within six months of the day it was issued.

Materials. Shingles, underlayment and flashing are delivered before day one. Tile is heavy, so it is often loaded onto the roof in stacks before or during the job.

Tear off. The old roof comes off down to the wood deck. This is the loud, dusty day. Any soft or rotten wood shows up now, and it gets replaced before anything new goes on.

The mid job inspection. The city's FAQ lists roof nailing among the common inspections and says work may not continue past each inspection point until the inspector approves it. In practice that means a day where the new deck or nailing has to be seen before the roof gets covered. Your roofer schedules it. If the inspector comes the next morning, the crew plans around that.

Dry in and new roof. New underlayment goes down, then flashing at walls, pipes and the edges, then the shingles or tile. This is the stretch that varies most by roof size and material.

Cleanup and final. The crew cleans up and sweeps the yard for nails. The city does a final inspection on the finished work. Keep the permit card and the final sign off with your house papers. You will want them when you sell.

Shingle vs. Tile, and Why Ontario Roofs Run Longer

A plain shingle roof on a one story ranch house is the fast case. It is light, it is quick to nail, and the crew can tear off and dry in one section at a time. That is where the national one to two day numbers come from.

Tile is a different job. Concrete and clay tile are heavy, each piece is set by hand, and every hip and ridge needs its own trim pieces. On a lot of tile roofs the owner also has a choice. Pull and reuse the good tile over new underlayment, or go to new tile. Either way it is more handling than shingles. Our tile roofing page explains that choice.

Size and shape matter as much as material. A two story house with lots of hips, valleys and a few skylights takes longer than a simple gable roof of the same size. So does a roof where the crew has to carry everything up a tall ladder because no room is left for a truck.

The energy code matters too. When more than half of a home's roof is replaced, California's cool roof rules can apply, per the California Energy Commission. Rated roofing products carry a Cool Roof Rating Council label. This does not slow the work much, but it does mean the product has to be picked before the permit, not on day two.

The rule is simple. Ask your roofer to write the expected number of working days into the quote, and to say what would add days. Rotten wood, an inspection that has to be rescheduled and weather are the usual three.

Rain, Santa Anas and Summer Heat

Nobody tears off a roof with rain coming. Once the old roof is off, the house is open until the new underlayment is down. So a forecast of rain pushes the start, and a surprise storm mid job means a tarp and a wait.

The good news is that real rain days are rare here. NOAA's 1991 to 2020 normals for Ontario International Airport show about 4.5 days with a tenth of an inch of rain or more in February, 3.4 in January and December, and almost none from June through August. Month by month, the average is 0.9 days in October, 1.8 in November, 3.4 in December and January, 4.5 in February, 2.7 in March and 1.8 in April. July averages just 0.1. A winter job may slide a few days. A summer job almost never waits on rain.

Wind is the other winter problem. Santa Ana days make it unsafe to carry sheets of underlayment and bundles across a roof, and a good crew will stop rather than lose a roll off the edge.

Summer has its own limit. The same NOAA normals show about 22.7 days at 90 degrees or hotter in an average July, and 23.8 in August. Under California's heat illness rule, shade has to be up when it is over 80 degrees, and construction is on the list of industries that must follow high heat procedures at 95 degrees. That means closer watching of the crew for heat illness and reminders to drink water. Many crews start at first light in July and August and wrap up by early afternoon, so a summer job can take an extra day on the calendar even when nothing goes wrong.

Can You Stay Home While the Roof Is Replaced?

Yes. Almost everyone stays home, and you do not need to move out. IKO says the same, but it suggests finding somewhere else for kids and pets on tear off day because of the noise and falling debris. We agree.

Living through it means noise, dust and a blocked driveway. Tear off day is loud from the first hour. Hammers and nail guns shake the ceiling, and pictures can walk off the wall. Dust and old granules can drift down into the attic, and sometimes through a loose attic hatch. The driveway is often blocked by a bin or a material truck.

Pets have the hardest time. A dog that barks at the mail carrier will not enjoy three days of people walking overhead. A day at a friend's house or a kennel on tear off day saves everyone a lot of stress.

If you work from home, plan your calls for the afternoon of the last day, or work from somewhere else on tear off day. The second half of the job is quieter, but not quiet.